An office machine such as a multifunction peripheral and an image scanning apparatus becomes an essential electronic device in the office. For successively feeding many paper sheets to increase the scanning speed, the multifunction peripheral and the image scanning apparatus are usually equipped with an automatic document feeder.
FIG. 1A is a schematic cross-sectional view illustrating a conventional automatic document feeder, which is disclosed in Taiwanese Patent No. TWI255253. As shown in FIG. 1A, the automatic document feeder 1 comprises an outer casing 11, an upper cover 12, a first relay roller 13, a second relay roller 14, a lever 15, a paper guide casing 16 and a paper pick-up module 17. A first end of the lever 15 is connected with the first relay roller 13. A second end of the lever 15 is sustained against a downward protrusion 121 of the upper cover 12. The middle portion of the lever 15 is fixed on a rear side of the first relay roller 13 through a fixing structure 151.
During a scanning operation is performed, the paper sheet to be scanned is transported through the paper guide casing 16 by the paper pick-up module 17, and then the paper sheet is pressed and clamped between the first relay roller 13 and the second relay roller 14 to be fed into internal portion of the automatic document feeder 1.
In a case that the paper sheet is jammed, the upper cover 12 should be uplifted to remove the jammed paper sheet, and then another paper sheet can be fed again to perform the scanning operation. FIG. 1B is a schematic enlarged fragmentary view illustrating a dotted circled portion of the automatic document feeder of FIG. 1A. Hereinafter, the action of the automatic document feeder for removing the jammed paper sheet will be illustrated with reference to FIG. 1B. Firstly, the upper cover 12 is rotated in the directional. Correspondingly, the second end of the lever 15 is pushed by the protrusion 121 of the upper cover 12, and the lever 15 is rotated in the direction a2 by using the middle portion of the lever 15 as a fulcrum. As the lever 15 is rotated in the direction a2, the first relay roller 13 is correspondingly moved in the direction a3, so that the first relay roller 13 is separated from the second relay roller 14. Meanwhile, the jammed paper sheet may be pulled out of the automatic document feeder 1 without difficulty.
From the above discussions, in the conventional automatic document feeder 1, the jammed paper sheet may be removed when the upper cover 12 is opened and the first relay roller 13 is separated from the second relay roller 14 through the lever 15.
The conventional automatic document feeder 1, however, still has some drawbacks. For example, since the lever 15 is fixed on the rear side of the first relay roller 13 through the fixing structure 151 and the lever 15 is sustained against the protrusion 121 of the upper cover 12, it is necessary for the conventional automatic document feeder 1 to provide an additional space to accommodate the lever 15 in order to achieve the function of removing the jammed paper sheet. As shown in FIG. 1, since there is an additional space at the rear side of the first relay roller 13, the overall volume of the conventional automatic document feeder 1 is increased.
Therefore, there is a need of providing an improved automatic document feeder so as to obviate the drawbacks encountered from the prior art.